Candida Sorbosa in Winemaking

Nowadays, consumers all over the world are concerned about the quality of food and beverages that they buy. Most of them have the inclination to look for products of organic farming like food and beverages because organic food is likely to contain lower residues of agricultural chemicals than non-organic food.

Wines are made with grapes that arecultivated according to the principles of biodynamic agriculture, a type of organic farming. The wine-making process has several steps namely hand harvest, soft crushing, vinification, and alcoholic fermentation. It has become widely common among oenologists that commercial selected yeast starters, mainly strains of Saccharomyces cerevisiae be used as starters to carry out the process. Nevertheless, this is a procedure that generally hinders both the development of non-Saccharomyces yeasts like Candida sorbosa owing to the fast production of ethanol, what favors the full exhaustion of sugars and the loss of genuineness, and the development of indigenous strains of S. cerevisiae that are forced to compete during the fermentation process with the commercial strains inoculated. The use of selected strains of S. cerevisiae has improved the fermentative processes and the quality of wines, but their continual use has led to a colonization and consequent elimination of the native microorganisms present in the wineries.

A study of over three years revealed that a large proportion of non-Saccharomyces strains were found after fermentation, representing 81% of all the yeasts isolated and only 19% of the isolations turned out to be Saccharomyces strains. Taking into consideration the fact that fermentation was used as an enriching medium in order to favor the growth of fermentative yeasts, such as S. cerevisiae, a high proportion of non-Saccharomyces yeasts were isolated and one of these was Candida sorbosa. However the population was found to be minimal compared to Candida stellata. Also, C. sorbosa of the Shiraz variety was found to exist in a conventional farm and not in an organic farm in a study done in 2011 with three grape varieties namely Shiraz, Grenache and Barbera made as focal points.

There is a need to come up with different strategies to isolate, identify and characterize different strains of both Saccharomyces and non-Saccharomyces yeast species from different vine-growing areas with typical traits so that wines of extraordinary characteristics will be produced. Furthermore, because the vineyard may be the main reservoir of native yeasts of oenological interest, it is necessary to preserve, and even encourage, the presence of fermentative species in it since they are better acclimatised to the environmental conditions and assure the maintenance of the typical sensory properties of the wines of a given region.